1. Technical Field
Aspects of this document relate generally to telecommunication systems and techniques for transmitting data across a telecommunication channel.
2. Background Art
One of the most difficult and resource-intensive parts of Direct Sequence Spread Spectrum (DSSS) receiver design is the initial synchronization of the spread code in the receiver. In some applications, both chip clock and carrier frequency offsets can be assumed to be extremely small such that a simple correlation can be performed between the incoming chipped symbol stream and the locally generated spread code. However, in most applications, particularly in satellite communications, the assumption of small carrier frequency offsets cannot be made. Therefore, some amount of frequency correction is required, even though chip clock rates between the transmitter and receiver can be assumed close enough.
There are two popular conventional acquisition methods of direct sequence spread spectrum signals. The first one uses FIR filter structure with the PN code sequence bits as the FIR filter coefficients (FIR method). Implementations of the FIR method can correlate in real time and fast. However, it is resource-demanding and extremely inflexible if there are any changes to the spreading factor.
The second conventional acquisition method uses one or multiple correlators to correlate the incoming DSSS signal sequentially (serial search method). Implementations of the serial search method result in considerable reduction in complexity. However, acquisition may be very slow as only m possible PN sequence shifts per frame may be searches, where m is the number of correlators.
So as to reduce the complexity and length of the Detailed Description, and to fully establish the state of the art in certain areas of technology, Applicant herein expressly incorporates by reference all of the following materials:
The following references are hereby incorporated by reference in their entirety:    [1] Bernard Sklar, Digital Communications: Fundamentals and Applications, Prentice-Hall, Inc., Englewood Cliffs, N.J., 1988.    [2]. Ir. J. Meel, Spread Spectrum (SS) Introduction, De Nayer Instituut, December 1999.    [3]. Ir. J. Meel, Spread Spectrum (SS) Applications, De Nayer Instituut, December 1999.    [4]. Application Note 1890, An Introduction to Direct-Sequence Spread-Spectrum Communications, Dallas Semiconductor, February 2003.    [5]. Erik Strom, etc., An Introduction to Spread Spectrum Systems, Chamlers University of Technology, Sweden, January 2004.
Applicant believes that the material incorporated above is “non-essential” in accordance with 27 CFR 1.57, because it is referred to for purposes of indicating the background of the invention or illustrating the state of the art. However, if the Examiner believes that any of the above-incorporated material constitutes “essential material” within the meaning of 37 CFR 1.57(c)(1)-(3), Applicant will amend the specification to expressly recite the essential material that is incorporated by reference as allowed by the applicable rules.